241. CHAPTER III. ON THE FORMATION OF THE CHICK IN THE EGG, AND ON THE ARTERIES, VEINS, AND RUDIMENTS OF THE HEART.
BELLINI. "Malpighi ... observes that there are many kinds of insects, including the silk worm, that are not furnished with a single heart, but with a number of hearts longitudinally disposed through the body, and which are of the figure of olives, and open one into the other. He observes, moreover, that these hearts do not pulsate simultaneously, but successively one after another in their places; the motion of the first being followed by that of the second, and so on in consecutive order. Furthermore, that creatures of this kind do not possess compound or collective lungs, situated in a given part of the body (as is the case with the human subject, and with numberless animals), but that they have air canals distributed through the whole body and all its parts; ... a most astonishing device, and at the first blush well nigh incredible.... These little creatures, with their many hearts and well aoerated frames, are everywhere provided with exceedingly viscid liquids, which in fact adhere most tenaciously both to their particular organs and structures, and to their bodies generally, at the surface of which latter they either remain at rest or are carried off. Hence it is that these liquids can be thrown to [only] a short distance by any instrument of propulsion, more particularly if impediments occur in the course of the passage; for they are separated with the greatest difficulty from the surface of such instrument, and adhere with the greatest readiness to the surfaces of all objects in their way.... But since it is requisite that these little creatures should be recruited and nourished by liquids thus constituted and distributed, and since these liquids are fitted for their offices by admixtion with air, hence, precisely in the same manner as in consequence of their sluggish nature, they cannot be derived into a single heart, so for the same reason, they cannot be derived into any single collective lung, situated in a separate and distinct part of the system, and company. (Opuscula Aliquot: De Motu Cordis, prop. ix., p. 58, 59; 4 to., Lugd. Bat., 1696.)
"Read Malpighi, and you will then understand how much the structure and motion of the heart and auricles differ at the commencement of generation, and for some days afterwards in the womb, from the structure and motion of the same heart and auricles after generation and out of the womb. But I will endeavor to explain this incredible subject in a few words, in order that the reader may understand the whole matter with less trouble than he must bestow in consulting the treatise of that author. Picture then to yourself a canal with a continuous cavity, but of unequal calibre or diameter in different parts; and suppose the wide parts or dilatations to be three in number, and the narrow to be four; then the whole length of the canal will be divided into seven parts, three of which are dilatations, and the other four contractions. The three dilatations, then, are elegantly arranged in the following manner: they do not succeed each other in direct sequence, but are each placed between two of the narrow parts, so that one end of the canal is constituted of one of the four narrow parts; this part is succeeded by the first of the dilatations; this, by the second of the narrow parts; this, by the second of the dilatations; this, by the third of the narrow parts; this again, by the third of the dilatations; the series being concluded by the fourth of the narrow parts, which constitutes the other end of the canal. Now, what do you think these parts respectively represent? The first of the narrow parts is the trunk of the vena cava; the first of the dilatations is the right auricle. The second narrow portion, placed between the right auricle and the second of the dilatstions, is a passage or meatus that conveys the blood from the right auricle into the second of the dilatations; and this second of the dilatations is the right ventricle. The third of the narrow parts, coming after the right ventricle, is a passage or canal that conducts the blood from the second of the dilatations into the third; and this third dilatation is the left ventricle. Finally, the fourth of the narrow portions, which concludes the series, is the trunk of the great artery. Is there anything in such a constitution of parts at all like the heart after generation and out of the womb? Here the trunk of the vena cava and the trunk of the great artery are in the same canal; the left ventricle, the right ventricle, and the right auricle, are in the same canal; and as for the left auricle, it is wanting altogether. Moreover, this canal is slightly curved in one portion. The blood is driven from the auricle into the right ventricle, and from the right ventricle immediately into the left, through the narrowed tube situated between the two. See how different the appearance of the heart and the motion of the blood at the time of their generation, and for some days afterwards in the womb, from the form of the same heart, and the motion of the blood, after generation, and out of the womb! But diversities and prodigies do not end here. Before many hours have elapsed, the whole canal, as far as the little tube that constitutes the third of the narrow parts, becomes more bent, and is turned upon itself, so that the right and left ventricles mutually approximate, and in a short time come in contact, and the intermediate canal is closed by turning upon itself: and at the same time the right auricle approaches nearer to the top of the right ventricle until it comes in contact with it; and the little tube that constituted the second of the narrow parts, is obliterated. After this, the pulmonary artery and the pulmonary vein issue from their respective ventricles, and the pulmonary vein has its auricle affixed to it above the left ventricle. What an incomprehensible series of things is here! What incomparable industry! How truly divine a process of fabrication!" (Ibid., prop. x., p. 65, 66.)
